FltRequestOperationStatusCallback function (fltkernel.h)
FltRequestOperationStatusCallback returns status information for the given I/O operation.
Syntax
NTSTATUS FLTAPI FltRequestOperationStatusCallback(
[in] PFLT_CALLBACK_DATA Data,
[in] PFLT_GET_OPERATION_STATUS_CALLBACK CallbackRoutine,
[in, optional] PVOID RequesterContext
);
Parameters
[in] Data
A pointer to the callback data (FLT_CALLBACK_DATA) structure for the I/O operation. This parameter is required and cannot be NULL.
[in] CallbackRoutine
A pointer to a callback routine that the Filter Manager calls after IoCallDriver returns. This parameter is required and cannot be NULL.
[in, optional] RequesterContext
A context pointer to be passed to the CallbackRoutine. This parameter is optional and can be NULL.
Return value
FltRequestOperationStatusCallback returns STATUS_SUCCESS or an appropriate NTSTATUS value such as one of the following:
| Return code | Description |
|---|---|
|
The minifilter driver's instance is being torn down. This is an error code. |
|
FltRequestOperationStatusCallback encountered a pool allocation failure. This is an error code. |
|
FltRequestOperationStatusCallback was called from a routine that was not a preoperation callback (PFLT_PRE_OPERATION_CALLBACK) routine, or the I/O operation was an IRP_MJ_CLOSE request. This is an error code. |
Remarks
A minifilter driver can call FltRequestOperationStatusCallback for an IRP-based I/O operation to obtain the status value that IoCallDriver returned for the operation.
Most minifilter drivers never need to call FltRequestOperationStatusCallback. Normally, a minifilter driver only calls this routine to determine whether a requested oplock was granted.
FltRequestOperationStatusCallback can only be called from a minifilter driver's preoperation callback (PFLT_PRE_OPERATION_CALLBACK) routine.
FltRequestOperationStatusCallback can only be called for non-IRP_MJ_CLOSE IRP-based operations. To determine whether the operation is an IRP-based operation, use the FLT_IS_IRP_OPERATION macro.
If the IRP-based operation is an IRP_MJ_CLOSE request, STATUS_INVALID_PARAMETER is returned.
FltRequestOperationStatusCallback copies the contents of the I/O parameter block (FLT_IO_PARAMETER_BLOCK) to the Iopb member of the callback data (FLT_CALLBACK_DATA), and this is the callback data that the Filter Manager will pass to the routine specified in the CallbackRoutine parameter. The copied data represents a snapshot of the I/O parameter block at the time that the preoperation callback (PFLT_PRE_OPERATION_CALLBACK) routine calls FltRequestOperationStatusCallback. If the preoperation callback routine changes the I/O parameter block after calling FltRequestOperationStatusCallback, the I/O parameter block that the Filter Manager passes to CallbackRoutine will be different from the I/O parameter block that the filter driver passes down the driver stack when it calls IoCallDriver.
The following example code from a preoperation callback routine illustrates how this might happen:
PFLT_CALLBACK_DATA Data;
PFLT_GET_OPERATION_STATUS_CALLBACK CallbackRoutine;
PVOID RequesterContext;
...
if (iopb->MajorFunction == IRP_MJ_READ) {
FltRequestOperationStatusCallback (Data, CallbackRoutine, RequesterContext);
Data->Iopb->Parameters.Read.ReadBuffer = newBuffer;
...
}
In the example, the read buffer is changed after the call to FltRequestOperationStatusCallback, so when the Filter Manager calls CallbackRoutine, it will pass in a pointer to the old buffer instead of the new one.
The Filter Manager calls the given CallbackRoutine in the context of the originating thread at IRQL <= APC_LEVEL.
Requirements
| Requirement | Value |
|---|---|
| Target Platform | Universal |
| Header | fltkernel.h (include Fltkernel.h) |
| Library | Fltmgr.lib |
| DLL | Fltmgr.sys |
| IRQL | <= APC_LEVEL |